Damn I had a long reply typed and somehow lost it to some editing function.
Just wanted to tell Keith that is exactly how sluice boxes work..heavier stuff stays behind when water flows across the load. Same thing should hold when wind or water erode soils, no? Has nothing to do with heaviest elements sinking towards the Earth's center when it was a molten ball. I think most gold comes from upheavals of Earth's crust through plate tectonics.
Wanted to mention I found one of the oldest types of human artifacts in North America, a Folsom spear point, lying on the surface on some sandy, never cultivated prairie in extreme SE WY. Shiny one topside, calcified on bottom. So it was still only half sunk after many thousand years.
Lloyd what happened to the pigs fed lead carbonate and lead sulfide? Were the concentrations fed expected to be toxic?
